In order to satisfy the functional diversification development of various kinds of electronic equipment, the composite circuit board has been widely used, because of their light, higher line density, etc.
Generally, the composite circuit board is formed by forming or bonding a flexible circuit board and a rigid circuit board together. The composite circuit board has many advantages of both the flexible circuit board and the rigid circuit board. In the process of the composite circuit board, the flexible circuit board is needed to plate copper thereon, second opening on local area of the composite circuit board to form a plurality of holes to expose of the flexible circuit board. However, plating copper always makes the flexible circuit board warp. Furthermore, opening to form holes on the flexible circuit board always may make the composite circuit board have bad electrical conductivity.